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Soil restraints on buried pipelines subjected to reverse-fault displacement

Authors :
Wijewickreme, Dharma
Monroy, Manuel
Honegger, Douglas G.
Nyman, Douglas J.
Source :
Canadian Geotechnical Journal. October, 2017, Vol. 54 Issue 10, p1472, 10 p.
Publication Year :
2017

Abstract

The interaction between a buried pipeline and surrounding soil during large ground displacements is typically simulated using numerical nonlinear soil-restraint springs aligned with the longitudinal axis of the pipeline and in the two directions orthogonal to it. There are only very limited experimental data available to characterize the soil springs for simulating pipelines crossing reverse faults where large oblique soil displacements relative to the pipe could occur. Full-scale model testing was undertaken to evaluate this complex soil-pipe interaction problem. The tests simulated the performance of ~400 mm diameter (nominal pipe size, NPS 16) pipe specimens buried in moist sand and crushed limestone trench backfill. The peak normalized oblique soil restraint ([N.sub.[theta]]) values for oblique pipe movement angles (0), when [theta] = 0[degrees] (horizontal movement) and [theta] = 90[degrees] (vertical movement), estimated based on state-of-practice approaches, were in agreement with those from full-scale testing. The value of [N.sub.[theta]] was found to depend significantly on the peak friction angle of soil ([[phi]'.sub.p]) when [theta] was closer to 0[degrees], whereas [N.sub.[theta]] was less sensitive to [[phi]'.sub.p] when [theta] was beyond about 35[degrees]. The theoretical values of [N.sub.[theta]] based on limit-equilibrium approaches compared well with the experimental findings. Key words: soil-pipe interaction, reverse-thrust fault crossings, earthquake-induced ground movements, buried steel pipelines, soil restraints on pipes. L'interaction entre une canalisation souterraine et le sol environnant lors de grands deplacements au sol est generalement simulee a l'aide de ressorts de restreints d'un sol non lineaire numerique simule et aligne avec l'axe longitudinal de la canalisation et dans les deux directions orthogonales a celle-ci. Il n'y a que tres peu de donnees experimentales pour caracteriser le ressort de sol pour la simulation de pipelines traversant les failles inverses ou de grands deplacements de sol oblique par rapport a la canalisation qui peut se produire. L'essai de modeles a grande echelle a ete entrepris pour evaluer ce complexe probleme d'interaction sol-conduite. Les essais ont simule le comportement de specimens de tuyaux d'environ 400 mm de diametre (dimension nominale du tuyau, NPS 16) enfouis dans de remblai de tranchee de sable humide et de calcaire concasse. Les valeurs de restreints de sol oblique normalise pic ([N.sub.[theta]]) pour des angles de deplacement de tuyau obliques ([theta]), lorsque [theta] = 0[degrees] (deplacement horizontal) et [theta] = 90[degrees] (mouvement vertical) estimes a partir d'approches de meilleures pratiques en accord avec ceux de l'essai a grande echelle. La valeur de N0 est averee significativement en fonction de l'angle de frottement pic de sol ([[phi]'.sub.p]) lorsque 0 etait plus proche a 0[degrees], alors que [N.sub.[theta]] etait moins sensible a [[phi]'.sub.p] lorsque [theta] a ete au-dela de 35[degrees]. Les valeurs theoriques de [N.sub.[theta]] basee sur des approches a la limite equilibre compare avec les resultats experimentaux. [Traduit par la Redaction] Mots-cles : interaction de tuyau au sol, passages de failles de poussee inverse, mouvements de terrain induits par le seisme, canalisations en acier enterrees, restrictions du sol sur les tuyaux.<br />Introduction Buried pipeline systems, including oil and gas pipelines, form an important part of lifeline infrastructure, and major disruption to the performance of these systems can result in undesirable impacts [...]

Details

Language :
English
ISSN :
00083674
Volume :
54
Issue :
10
Database :
Gale General OneFile
Journal :
Canadian Geotechnical Journal
Publication Type :
Academic Journal
Accession number :
edsgcl.510482061
Full Text :
https://doi.org/10.1139/cgj-2016-0564